1. Field of the Invention
This invention relates in general to three dimensional (3D) computer aided design (CAD) systems, and more particularly, to a method, apparatus and article of manufacture for generating reverse daylighting on a surface on a computer-generated image.
2. Description of Related Art
Daylighting of surfaces is used in 3D CAD systems to illustrate to the user the shape of a surface and to indicate the projection of a surface from an intersecting point or line.
Present methods require the user to perform additional operations, such as adding vertices on entities or objects within the drawing to define the resolution for the daylighting. For large objects being daylighted, the extra operation of adding vertices requires additional user time to create the completed CAD drawing, making the CAD drawing more expensive and more time consuming to complete.
Further, volume calculations are performed using the daylighted projection lines. The use of too few or too many vertices as described above will affect the precision and accuracy of volume calculations performed by the computer.
It can be seen, then that there is a need in the art for a more uniform method for creating daylighted objects. It can also be seen, then, that there is a need in the art for a daylighting method that is faster and less expensive. It can also be seen that there is a need in the art to improve the accuracy of volume calculations by creating a uniform method for creating daylighted objects.